This is a pilot study designed to identify and quanititate key factors which contribute to the variability of vascular responses to the intra arterial infusion of insulin in a population of older adults with NIDDM. To accomplish this aim, we will test the experimental protocol and characterize the variability of the measures to be obtained. The proposed studies will focus on the following Research questions: 1. In subjects with NIDDM compared to healthy control subjects is there: a) resistance to the insulin-mediated vasodilation, and b) decreased production of biomarkeres of nitric oxide (NO) production during insulin infusion? 2. Among subjects with NIDDM, are the vasomotor responses to the intraarterial insulin infusion among those subjects with hypertension even more impaired than those without hypertension? The experimental techniques required include: 1)forearm blood flow (FABF) determinations using venous occlusion plethysmography and 2)measurements of biomarkers of NO production. The FABF protocol will involve the intra-brachial artery infusion of insulin. These pilot studies are designed to determine the insulin dose necessary to produce consistent changes in FABF in this study population. During the infusion of escalating concentrations of insulin, FABF and blood samples for insulin levels will be drawn. We will measure levels in the ipsilateral and contralateral arms to evaluate respectively local and systemic levels of insulin. Venous samples will also be drawn at the various insulin concentrations for biomarkers of nitric oxide activity (nitrite/nitrate,, citrulline and cGMP) to define the local and systemic levels of biomarkers of nitric oxide production during insulin infusion. The results of this pilot study will form the basis for a subsequent intervention study to determine whether improvement in metabolic insulin resistance in older adults with NIDDM results in improvement in vasomotor insulin resistance.